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¡ Semiconductor

MSM82C54-2RS/GS/JS

DESCRIPTION OF BASIC OPERATIONS

Data transfers between the internal registers and external data bus is outlined in the following

table.

DESCRIPTION OF OPERATION

MSM82C54-2 functions are selected by control words from the CPU. In the required program

sequence, the control word setting is followed by the count value setting and execution of the

desired timer operation.

Control Word and Count Value Program

Each counter operating mode is set by control word programming. The control word format

is outlined below.

SC1

SC0

RL1

RL0

M2

M1

M0

BCD

Select Counter

Read/Load

Mode

BCD

0

0

0

0

0

CS

Function

0

0

0

1

0

1

1

1

0

1

RD

0

0

0

¥

1

0

0

0

1

0

WR

1

1

1

¥

1

0

1

1

0

0

0

1

1

¥

¥

1

0

1

0

0

1

0

1

¥

¥

Data Bus to Counter #0 Writing

Data Bus to Counter #1 Writing

Data Bus to Counter #2 Writing

Data Bus to Control Word Register Writing

Data Bus from Counter #0 Writing

Data Bus from Counter #1 Writing

Data Bus from Counter #2 Writing

Data Bus in High Impedance Status

¥: denotes "not specified"